JP2742430B2 - Intermediate buffer for communication cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an intervening buffer for a communication cable. The purpose of the present invention is to stop water running at an insulating layer portion even if the outer cover is damaged. An object of the present invention is to provide an intervening buffer for a communication cable that can suppress a leakage or a communication failure.

(Prior art) Conventionally, paper cords, synthetic resin cords, non-woven fabrics or glass fibers, asbestos fibers, cotton yarns and other yarns have been used as intervening buffers for communication cables. Specifically, filling the intervening buffer between the multi-core cables during cable manufacturing,
The core wire and the covering material are integrated and the cross section is rounded to suppress water running with this interposed buffer. The required performance of the interposed buffer is that it is flexible and does not contaminate the adjacent insulator. It is.

In a power cable for preventing water running, if a part of the outer protective layer of the cable is damaged, water runs in the cable, and the electrical characteristics are damaged over the entire length of the electrical insulator. The cable may be broken due to deterioration. Not only ordinary wire and cable,
Also in the optical fiber cable, breakage of the optical fiber is caused by the intrusion of water. In order to prevent these troubles, various waterproof cables have been proposed.

For example, Japanese Utility Model Application Laid-Open No. 56-139109 discloses a waterproof mixture in which an anionic water-absorbing resin such as sodium polyacrylate is added to a petrolatum-based or polybutene-based jelly-like waterproof mixture. An optical fiber submarine cable is disclosed. In addition,
Japanese Patent Application No. 60-150506 discloses that a water-swelling synthetic polymer having a specific high water-absorbing property is applied to at least one surface of a nonwoven fabric as a substance for preventing water running in a cable as an intervening buffer layer. A protective power cable is disclosed.

(Problems to be Solved by the Invention) However, according to the former technique disclosed in Japanese Utility Model Application Laid-Open No. 56-139109, a water-blocking effect can be obtained by filling all the voids in the buffer layer. Filling is difficult due to the jelly shape. In other words, the method of filling jelly mixed with water-absorbent resin powder is to fill the unfilled part with the water-swelling expansion of the water-absorbent resin, thereby eliminating the unfilled part and preventing water running. Since it is wrapped in petrolatum-based or polybutene-based jelly with low water permeability, the infiltrated water is not completely absorbed, causing water to run, resulting in inferior performance as a waterproof cable. In addition, when using this kind of jelly, there is also a problem that it is difficult to process the connection of the cable terminal with dirt. In the latter technique disclosed in Japanese Patent Application Laid-Open No. 60-150506, a water-absorbing resin powder is applied to a synthetic resin string or the like and used as an intervening buffer layer. Since the water-absorbing resin is adhered to a relatively flat form, there are few places where the water-absorbing resin is deposited, and it is difficult to attach a large amount of the water-absorbing resin. For this reason, if more water-absorbent resins are to be attached, the water-absorbent resins will aggregate or adhere to each other, and when the intruded water comes into contact with the water-absorbent resin mass, only the surface of the water-absorbent resin mass will be applied. Will swell. On the contrary, the water-absorbent resin swelling only on the surface forms a water barricade, and prevents the water-absorbent resin that has not yet absorbed water from absorbing water. It cannot be done.

As described above, the above-described invention has a problem that water running cannot be sufficiently suppressed in any case. Also, interposed cushioning materials for cables in which a water-absorbing resin is attached to the surface of slit yarns and split yarns made of synthetic resin have been proposed, but they have the same problems as those of the non-woven tape described above. The texture of the interposed buffer also has a hard defect. It has been proposed to use water-absorbing cellulose fibers as an intervening buffer. However, when water from seawater or soil is absorbed, microorganisms contained in these materials cause deterioration of the material, resulting in a decrease in cable strength. Currently, it has not been put to practical use.

As described above, the various techniques proposed in the related art cannot completely prevent water that has penetrated from a damaged portion on the surface of a cable from running, and also have a problem that bacteria such as bacteria such as rainwater and seawater are not allowed to run. As a result, the filler in the intervening buffer layer is damaged and deteriorated, and the cable and the like are apt to break. For this reason, as an intervening buffer for a communication cable such as an optical cable, a substance that is antimicrobial degradable and that can prevent water running has not been obtained. The present inventors have already disclosed in Japanese Patent Application No. 62-75006 (Japanese Patent Application Laid-Open No. 63-241806) the purpose of improving the above-mentioned prior art, as a carrier for an intervening buffer, which is less susceptible to flexible microbial degradation. In addition, there has been proposed a fiber obtained by depositing a water-absorbing resin which is hardly susceptible to microbial decomposition on a synthetic fiber crimped yarn having a large surface area of the fiber surface. However, when a crimped yarn is used, the crimped yarn is stretched due to the tension during processing during processing of a water-absorbent resin or filling a communication cable, and therefore the fiber surface is effectively filled with the water-absorbent resin. Although the water running performance has been improved from the past, the stopping performance of the water running was still insufficient.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned problems of the prior art, and is a synthetic fiber crimped yarn that is flexible and is not easily susceptible to microbial degradation as a carrier for an intervening buffer. And the crimped yarn is hardly deformed by external force, so that the surface area of the fiber surface can be kept large.
Further, they have found that the crimped form is suitable for depositing a water-absorbent resin, and have reached the present invention.

That is, the present invention relates to an interposer for a communication cable in which a water-absorbent resin having excellent antimicrobial degradability is deposited on the surface of a composite yarn consisting of a crimped yarn composed of synthetic fiber which is not easily degraded by microorganisms and a tensile yarn. The subject matter is a buffer.

 Hereinafter, the present invention will be described in detail.

First, FIG. 1 shows a sectional view of an optical fiber communication cable as an embodiment of a waterproof cable. (1) is a central tensile member, (2) is an optical fiber core wire, (3) is an intervening buffer layer, (4) is a holding tape, (5) is an outer semiconductive layer,
(6) is a sheath part. Normally, in a waterproof type optical fiber communication cable, a water blocking function (also referred to as a water stopping function) is provided between the optical fiber core wire (2) and the external semiconductive layer (5).

Next, the synthetic fibers used in the present invention are polyamide,
Multifilament yarns made of polyester, polyolefin, etc., that are resistant to microbial degradation by bacteria such as bacteria contained in seawater or soil sewage, and resistant to material degradation (also called antimicrobial degradability). It is. Generally, synthetic fibers have better antimicrobial degradability than animal fibers such as cellulosic fibers, wool, and silk, and do not cause a decrease in material strength even when buried in soil or seawater for a long time. It has been known. However, recently, fiber modification such as hygroscopicity and antistatic has been actively performed.
Since additives, polymer modifiers, oils, and the like are often contained in synthetic fibers, antimicrobial degradability is required not only for the base polymer but also for the intervening buffer for communication cables. On the other hand, natural fibers and regenerated fibers such as cotton yarn, jute, wool, silk and rayon are not suitable for the purpose of the present invention because they are hydrolyzed in the fiber material by bacteria such as bacteria to cause deterioration of the cable material.

As a method for producing a crimped yarn, a method generally called bulking can be adopted, and specifically, it can be produced by any of the false twisting method, the indentation method, the rubbing method, the air injection method, and the like. . FIGS. 2 and 3 show a crimped yarn and a curled yarn as one embodiment of a crimped yarn. Heat crimping and indentation methods are preferred for obtaining crimped yarns, and rubbing and false twisting methods are preferred for obtaining curled yarns.

In addition, in order to increase the bulkiness and increase the fiber surface area, the cross-sectional shape of the filament is changed to a Y-shape, X-shape or the like, so that the place where the water-absorbing resin is deposited increases, and a favorable result is obtained. Is not limited to this.

The tensile strength yarn is not a material having elasticity like a crimped yarn, and the yarn is a straight yarn having no crimp, a high strength, and a yarn that is hard to expand against external force. The tensile strength yarn is drawn together with the crimped yarn, and if necessary, twisted to form a composite yarn. The function of the tensile strength yarn is to prevent the crimp from being completely extended by the working tension when depositing the water-absorbent resin on the crimped yarn or filling the communication cable.

As the water-absorbing resin having excellent antimicrobial decomposability, a polyacrylic acid-based copolymer, a vinyl acetate-acrylic acid-based copolymer, an isobutylene-maleic anhydride-based copolymer, and the like are preferable. Starch-based or cellulose-based water-absorbing resins are not preferred because they are decomposed by bacteria such as bacteria contained in seawater or soil sewage, and cause deterioration of cable materials. Here, antimicrobial degradability is desirable to investigate whether biodegradation by bacteria such as bacteria is actually buried in soil, but it takes time for evaluation, so in the present invention, it is evaluated by the following accelerated test method. did.

First, 300 cc of muddy water was collected from a river, filtered with filter paper, and 0.6 g of NH ₄ H ₂ PO ₄ was added.
Those that were left for 100 days at 30 ° C. and did not generate hydrogen gas were judged to have high antimicrobial degradability.

In order to deposit the water-absorbent resin on the surface of the crimped yarn, the crimped yarn is deposited by impregnating or coating a resin solution in which the water-absorbent resin is dissolved or dispersed in an appropriate organic solvent or the like. If the water-absorbent resin has poor adhesion to the yarn, a binder such as an acrylic resin, a vinyl chloride resin, or a urethane resin may be used in combination as long as the water-absorbency is not impaired, and deposited.

Next, as for the amount of the water-absorbing resin deposited, it is desirable that the water-absorbing resin is deposited as much as possible uniformly so as not to form a lump. Normally, it is preferable to attach about 10 to 35% by weight to the fiber weight. The amount of deposition varies depending on the number of filaments, fineness, cross-sectional shape, etc. of the crimped yarn, but the above-mentioned amount of adhesion is preferable in order to prevent water running. The deposition may be performed twice or more for the purpose of uniform deposition.

(Action) According to the present invention, an interposed buffer having a high water-running inhibiting effect can be obtained by depositing a water-absorbent resin having high antimicrobial degradability on a crimped yarn made of synthetic fibers having antimicrobial degradability.

For this reason, the present inventors speculate as follows.

First, by using a crimped yarn made of synthetic fibers having antimicrobial degradability, the surface area of the crimped yarn is larger than that of a conventional tape or nonwoven fabric, so that the amount of the water-absorbent resin deposited increases.

Next, in the present invention, by using a composite yarn, unlike a tape or a nonwoven fabric, it is possible to deposit a water-absorbent resin not three-dimensionally but three-dimensionally. Will be dramatically improved. In addition, since the water-absorbent resin carrier is a composite yarn containing a crimped yarn made of a flexible synthetic fiber, it is flexible even when the water-absorbent resin is deposited, and has impact resistance to external forces. Resistance to cutting increases. Furthermore, since the crimpability of the crimped yarn is prevented from being stretched by the tensile strength yarn, the crimped yarn can be protected from the processing tension when depositing the water-absorbent resin and filling the cable with the crimped yarn. Water running prevention effect becomes high. Since the crimped yarn and the water-absorbent resin have high antimicrobial decomposability, even if sewage containing bacteria such as bacteria invades, it is hardly susceptible to microbial degradation, thereby suppressing material degradation and preventing cable cutting. .

As described above, by using the intervening buffer of the present invention, it is possible to prevent, for the first time, water running in from the break portion of the cable. In addition, since the intervening buffer is flexible, manufacture of the water stoppage cable becomes easy.

(Examples) Hereinafter, the present invention will be described specifically with reference to examples.

First, the methods for evaluating the water absorption, the water running property and the antimicrobial degradability evaluated in Examples and Comparative Examples are shown below.

(1) Measuring method of water migration Using a measuring device shown in Fig. 5, a glass tube with an inner diameter of 5 mm (1
1) The yarn on which the water-absorbent resin to be measured is deposited
It is called a water-absorbing thread. ), Connect it to a Teflon tube made of polytetrafluoroethylene resin (12), and add NaCl 0.75 g / Cacl ₂ 0.5 g / The solution in which was dissolved was introduced, and the distance traveled by the glass tube (9) was measured.

 The filling ratio was determined by the following equation.

(2) Antimicrobial degradability First, the muddy water collected in the Uji River was filtered using filter paper (Toyo Roshi Kaisha, Ltd.).
0.6 mL of NH ₄ H ₂ PO ₄ in 300 ml of muddy water filtered with a product, filter paper No. 1)
g, add 4 g of water-absorbing yarn to be evaluated, and after sealing, 30 ° C 1
After being left for 00 days, those in which no generation of hydrogen gas was observed were judged to have excellent antimicrobial degradability.

Example 1, Comparative Examples 1-2 Nylon 6BCF bulky processed yarn 3000 denier 144 filament (product of Unitika Ltd., P-600) and nylon 6,210 denier 24 filament (unitika product, P-820) of 25T twist. / M twisted with a polyacrylate-based water-absorbent resin solution (Toppan Printing Co., Ltd. product, each product H-2, solid content concentration 38%, solvent toluene / methyl ethyl ketone VoL ratio 1:
It was immersed in 1), drained with a mangle at a squeezing ratio of 65%, and deposited 25% per fiber weight. Observation of the obtained water-absorbing thread showed that the water-absorbing resin was deposited between the filaments and the resin was deposited three-dimensionally. Next, the water absorption inhibiting ability and antimicrobial degradability of the obtained water-absorbing yarn were evaluated, and the results are shown in Table 1.

For comparison with the present invention, the following comparative test was performed. In Comparative Example 1, the nylon 6BCF bulky textured yarn of Example 1 was used with 3000 denier 144 filament alone.
A water-absorbing thread was produced in the same manner as in Example 1 except for the above. Next, the performance of the obtained water-absorbing yarn was evaluated, and the results are shown in Table 1.

In Comparative Example 2, a water absorbent resin was used in Example 1. Instead of polyacrylate resin, use carboxymethyl cellulose (degree of polymerization 400, degree of etherification 0.6, CMC in Table 1)
It was described. Production of a water-absorbing thread was carried out in the same manner as in Example 1 except that the chlorinated ethylene-vinyl acetate copolymer was changed to a toluene dispersion solution (solid content: 38%) in which 8% was added to the dry weight of the water-absorbent resin. went. Table 1 shows the results of water absorption performance of the obtained water-absorbing yarns. As is clear from the table, the filling rate of the intervening buffer is almost the same, but the material has a higher water-stopping ability and a higher antimicrobial degradability than the comparative example. Deterioration can also be prevented.

(Effects of the Invention) As described in detail above, according to the present invention, a composite yarn of a bulky synthetic fiber crimp-processed yarn and a tensile yarn, which is hardly susceptible to microbial degradation, is used as a carrier of an antimicrobial degradable water-absorbent resin. This makes it possible to deposit water-absorbent resin three-dimensionally without losing bulkiness due to processing tension, to achieve uniform dispersion of water-absorbent resin, and to run water that has penetrated from damaged parts on the cable surface. Water can be stopped in a short range of water. Further, since the material is not deteriorated by bacteria such as bacteria, it can be applied to the field buried in the sea or soil.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of an optical fiber communication cable, FIG. 2 is an explanatory view of a crimp yarn showing one embodiment of a bulky yarn subjected to crimping by indentation, and FIG. FIG. 4 is an explanatory view of a curled yarn showing one embodiment of a bulky processed yarn that has been crimped, FIG. 4 is an explanatory view showing one embodiment of a composite yarn of a bulky processed yarn and a tensile strength yarn, and FIG. It is explanatory drawing of the water running test which evaluates the water running inhibiting ability of the intervention buffer. DESCRIPTION OF SYMBOLS 1 ... Center tensile body 2 ... Optical fiber core wire 3 ... Intermediate buffer layer 4 ... Holding tape 5 ... External semiconductive layer 6 ... Sheath part 7 ... Crimped thread, 8 ... Curl Processed yarn 9: Bulk processed yarn, 10: Tensile yarn 11: Glass tube 12: Polytetrafluoroethylene tube 13: Tank

Claims (1)

(57) [Claims] An intermediary buffer for a communication cable comprising a composite yarn comprising a crimped yarn and a tensile yarn made of a synthetic fiber which is hardly susceptible to microbial degradation, and a water-absorbent resin having excellent antimicrobial degradability deposited on the surface of a composite yarn. Stuff.